1. Field of the Invention
The present invention relates to a preparation process of phenol aralkyl resins, and more particularly, the invention relates to a method for preventing adhesion of scale to the internal surface of manufacturing equipment in the manufacture of phenol aralkyl resins.
2. Related Art of the Invention
It has been known that a solvent-insoluble polymer adheres to the interior of a reactor in the manufacture of various synthetic resins. The adhered polymer is called scale, cullet or built up. Adhesion of scale to the internal wall of a reactor and the stirring blades impairs heat conduction of the reactor and. reduces effectiveness of heat exchange of the reactor. Further, when the adhered scale peels off and contaminates the resin product, the quality of the product is extremely impaired and moreover, possibility of blocking is developed in the various pipe arrangements which connect with the reactor.
Japanese Laid-Open Patent HEI 7-304806 has disclosed in the preparation of a vinyl chloride based polymer, a preparation process which can prevent adhesion of the polymer scale to the reactor by adding an initiator to the charged mixture and successively maintaining the temperature of the heating medium which runs through the jacket in a range between temperature of the charged mixture and temperature of preset polymerization temperature +4.degree. C. or less.
As to preparation of phenols, Japanese Laid-Open Patent HEI 7-236801 has disclosed a technique for giving mechanical vibration and thus preventing scale adhesion to a heat transfer tube mounted on the interior of a still. As to phenol resin, Japanese Patent Publication SHO 57-26606 has disclosed preparation equipment of phenol resin which can cool the upper portion of an evaporator and the connecting pipe between the evaporator and a mist separator. Scale adhesion to the internal surface of the connecting pipe can be inhibited by cooling the connecting pipe.
As to preparation process of phenol aralkyl resins, Japanese Laid-Open Patent HEI 6-100667 has disclosed a preparation process of a high purity phenol polymer by reacting a phenol compound in the absence of a catalyst with an aromatic compound represented by the general formula; EQU R--(CH.sub.2 X).sub.2
wherein R is a phenylene group, alkyl substituted phenylene group, biphenylene group, divalent diphenyl ether group or naphthylene group, and X is a halogen atom.
The preparation process is characterized ir that a phenol polymer is prepared by condensation of an aromatic compound with a phenol compound without using a catalyst. The phenol polymer obtained by the process is a high-purity excellent polymer and does not contain acid constituent or metallic ingredient. However, no disclosure is found in the patent on the method for preventing scale adhesion to the interior of manufacturing equipment.
At present, mechanical clearance is generally carried out on the scale of phenol resin, phenol aralkyl resin in particular, which adheres to the interior of manufacturing equipment. Mechanical clearance cannot completely remove the scale, and additionally, has the risk of troubles for causing breakage of the equipment and the problems of decrease in the operating efficiency of the equipment due to peeling operation.
In view of the above problems, the object of the invention is to provide a preparation process of phenol aralkyl resin which can prevent scale adhesion to the interior of manufacturing equipment.